Series resonant trap and method of making same



M. H. JACOB March 25, 1969 SERIES RESONANT TRAP AND METHOD OF MAKING SAME File'd Nov. 50. 1964 United States Patent ()fice 3,435,386 Patented Mar. 25, 1969 3,435,386 SERIES RESONANT TRAP AND METHOD OF MAKING SAME Marvin H. Jacob, Volin, S. Dak., assignor to Dale Electronics, Inc., Columbus, Nebn, a corporation of Nebraska Filed Nov. 30, 1964, Ser. No. 414,605 Int. Cl. H01h 7/00 U.S. Cl. 333-76 4 Claims ABSTRACT OF THE DISCLOSURE A resonant trap device including an elongated insulative core with terminal means on opposite ends of the core. A coil of wire material is wound on the core and is comprised of two strands of electro-conducting wire having opposite ends. One end of one strand of wire is secured to one of the terminal means and the opposite end of the other strand of wire is secured to the other terminal means. The coil of wire material also includes an insulative coating which maintains the strands together in a spaced relation.

A series resonant trap serves the function of regulating or controlling the frequency being fed through an electrical circuit such as an amplification system. It is desirable in such cases to maintain or achieve a certain level at a specific frequency or band of frequencies. Elforts have been made to accomplish this by linking individual inductor and capacitor combinations. This method is quite costly because of components plus the cost of assembly, also precise control of resonate frequency is very diflicult to achieve because it entails tolerance of two individual components.

Therefore, a principal object of this invention is to provide a series resonant circuit employing inductance and capacity that will resonate at the desired frequency thereby achieving a low value of impedance at this frequency.

A further object of this invention is to provide a series resonant trap and method of making same employing a combination inductive-capacitance effect whereby the inductance and capacitance can be easily and accurately controlled.

These and other objects will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, and combination, of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawing, in which:

FIGURE 1 is an elevational view of the device of this invention;

FIGURE 2 is a side schematic view of the components employed in bonding the separate wires together in parallel fashion;

FIGURE 3 is a schematic plan view of the components of FIGURE 2;

FIGURE 4 is an enlarged sectional view of the two wires as they would appear on line 44 of FIGURE 2;

FIGURE 5 is an enlarged sectional view of the bonded wires as they would appear on line 5-5 of FIGURE 2; and

FIGURE 6 is a perspective view of the wire being bonded by the apparatus of FIGURES 2 and 3.

The numeral 10 generally designates the resonant trap unit which includes a cylindrical core 12 of insulative material, such as a phenolic plastic, with axial terminal leads 14 and 16 embedded in the ends thereof. A coil of electro-conducting wire material 18 is wound upon core 12, and the wire is placed upon the core through the use of what is known in the trade as a universal winding.

The structure of the wire material 18 is of exceptional importance. It is comprised of two strands of wire 20 and 22 which have a relatively thin insulation layer 24 thereon of conventional material. As shown in FIG- URE 4, each wire then has a further layer 26 thereon which serves as a combination insulation and bonding layer and is comprised of a solvent sensitive thermoplastic resin varnish.

As shown in FIGURES 2 and 3, the two strands of wire 20 and 22 are introduced in parallel side by side condition into container 27 which holds a quantity of solvent 27A such as acetone. As the strands of wire are passed into the acetone as indicated by the arrows in FIGURE 2, the solvent softens the insulation and bonding layer 26 on each strand of wire which causes the respective coatings 26 on the respective wire strands to fuse together as they pass from the solvent into the atmosphere to form a combined insulation layer 26A (FIGURE 5). The bonded two strand wire material 18 of FIGURES 5 and 6 results from this process and it maintains the strands of wire '20 and 22 in an absolute parallel and uniformly spaced condition. This permits the capacitance of a length of wire material 18 to be easily and accurately measured. The inductance created by winding the wire material about the core 12 is easily controlled by carefully determining the number of turns on the coils according to known procedures. Thus, by controlling the number of turns of wire material 18, the inductance can be controlled, and by controlling the length of the wire material containing the two uniformly spaced wire strands 20 and 22, the resulting capacitance is measured, controlled and predetermined even before the wire material is wound on the core 12. Through having absolute control of the inductance and the capacitance, the frequency that the trap will ultimately pass can also be absolutely controlled.

After the wire material 18 has been fabricated as described above, and then cut to the proper length to provide the desired capacitance, it is wound on core 12 according to any convenient winding method. As shown in FIGURE 1, the end 20A of wire strand 20 is electrically secured to terminal 14 in any convenient manner, such as by soldering, and the opposite end 20B of strand 20 is merely left in an exposed condition. The end 22A of wire strand 22, which is on the same end of the coiled wire material 18 as the end 20A of wire strand 20, is left in an exposed condition, and the opposite end 22B of strand 22 is secured to terminal 16. The two uuterminated ends 20B and 22A produce the desired capacitance effect between the wire strands 20 and 22. This capacitance is a uniformly distributed capacitance because of the precise parallel positions of the wire strands 20 and 22 in the coiled wire material 18. As a consequence we have a precisely controlled capacitor built into the inductor. The resonate frequency (minimum impedance) of the device can be changed by altering the length of the winding, which will change capacity or by changing the winding pattern of the universal winding which will change the flux linkage within the coil.

While this invention is not to be limited to precise electrical values, wire strands 20 and 22 having a diameter of 0.041 inch have been successfully used. If the desired frequency to be passed is 10.7 megacycles, the resistance or impedance of the unit at resonance will be approximately 10 ohms.

This invention provides a resonant trap device which will easily and accurately serve to purify a desired fre- 3 quency in an electrical system to a predetermined level, and as such, this invention achieves at least all of its stated objectives.

Some changes may be made in the construction and arrangement of my series resonant trap and method of making same without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim: 1. In a resonant trap device, an elongated insulative core, terminal means on opposite ends of said core, a coil of wire material wound on said core, said coil of wire material comprising two strands of parallel electroconducting wire and having opposite ends, with only one end of one strand of Wire being secured to only one of said terminal means, and only the opposite end of said other strand of wire being secured to said other terminal means. 2. In a resonant trap device, an elongated insulative core, terminal means on opposite ends of said core, a coil of Wire material wound on said core, said coil of wire material comprising two stands of electro-conducting wire and having opposite ends, with only one end of one strand of wire being secured to only one of said terminal means, and only the opposite end of said other strand of wire being secured to said other terminal means; said coil of wire material including an insulative coating holding said strands of wire together in a parallel side-by-side spaced relation. 3. In a resonant trap device, an elongated insulative core, terminal means on opposite ends of said core, a coil of wire material wound on said core, said coil of wire material comprising two strands of electro-conducting wire and having opposite ends,

with only one end of one strand of wire being secured to only one of said terminal means, and only the opposite end of said other strand of wire being secured to said other terminal means;

said coil of wire material including an insulative coating holding said strands of wire together in a parallel side-by-side spaced relation;

said terminal means comprising elongated leads imbedded in opposite ends of said core.

4. The method of making a resonant trap device, comprising,

taking two strands of wire coated with a layer of combination bonding and insulative agent,

passing said strands of wire in parallel condition through a bath of bonding agent reactant material to join the layers on said strands together into a composite wire material,

cutting a portion from the length of said wire material,

winding said portion on a core means having separate terminals on its opposite ends,

connecting only one end of one strand of wire to one of said terminals, and connecting only the other end of said other strand of wire to said other terminal.

References Cited UNITED STATES PATENTS 3,125,733 3/1964 Holinbeck 33379 3,004,229 10/1961 Stearns 33384 3,076,947 2/1963 Davidson 333-79 3,191,132 6/1965 Mayer 333-79 3,227,974 1/1966 Gray 33379 H. K. SAALBACH, Primary Examiner.

C. BARAFF, Assistant Examiner.

US. Cl. X.R. 

